/*
Copyright 2021 LuJun

Permission is hereby granted, free of charge, to any person obtaining a copy 
of this software and associated documentation files (the "Software"), to deal 
in the Software without restriction, including without limitation the rights 
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
copies of the Software, and to permit persons to whom the Software is furnished 
to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in 
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

import { error, EventTarget } from 'cc';
import { DEFAULT_ASYNC_WAIT_TIMES, EVENT_ASYNC_COMPLETE } from './base';
import { timer } from './timer';

const TAG = 'lcc/core/async.ts';

/**
 * @zh
 * 异步模块
 * 主要管理异步操作
 */
export class Async extends EventTarget {
    /**
     * @zh
     * 异步计数
     */
    private _count: number = 0;

    /**
     * @zh
     * 异步计数
     */
    get count() {
        return this._count;
    }

    /**
     * @zh
     * 检查异步完成
     */
    private checkComplete() {
        if (this._count <= 0) {
            try {
                this.emit(EVENT_ASYNC_COMPLETE);
            } catch (e) {
                error(TAG, `checkComplete Exception ${e}`);
            }
        }
    }

    /**
     * @zh
     * 增加异步
     */
    inc() {
        this._count++;
    }

    /**
     * @zh
     * 减少异步
     */
    dec() {
        this._count--;
        this.checkComplete();
    }

    /**
     * @zh
     * 异步完成
     *
     * @param waitMax 等待最大次数，默认[DEFAULT_ASYNC_WAIT_TIMES]
     *
     * @returns boolean 异步是否完成
     */
    async complete(waitMax = DEFAULT_ASYNC_WAIT_TIMES) {
        let waitTimes = 0;
        while (waitMax === -1 || waitTimes < waitMax) {
            if (this._count <= 0) {
                return true;
            } else {
                await new Promise<any>((resolve) => {
                    this.once(EVENT_ASYNC_COMPLETE, resolve);
                });
            }
            await timer.toNextFrame();
            waitTimes++;
        }
        return false;
    }
}

/**
 * @zh
 * 全局异步IO对象
 */
export const asyncIO = new Async();
